Serum proteins, lipoproteins, and glycoproteins in muscular dystrophy and related diseases

Sialic acid content in serum IgG from patients with myotonic dystrophy compared with healthy controls

One of the determinants of the lifetime of circulating glycoproteins is their content of the terminal carbohydrate sialic acid. In order to elucidate a possible mechanism behind reduced concentration of IgG in patients with myotonic dystrophy, serum IgG was isolated by affinity chromatography and its content of sialic acid determined. No difference between patients and healthy controls was found. The results provide further support to the idea that a host factor rather than an abnormality of the IgG molecule itself is responsible for the low concentration of serum IgG in this disease.

Elevated plasma levels of haptoglobin in Duchenne muscular dystrophy:electrophoretic variants in patients with a severe form of the disease

Analysis of plasma proteins of Duchenne muscular dystrophy (DMD) patients and normal age-matched boys using two dimensional gel electrophoresis and densitometry indicated a three-fold increase in the average haptoglobin level in DMD plasma. Two electrophoretic variants of haptoglobin in which the alpha 2 chain had more basic or more acidic spots were found in DMD patients with a rapidly progressing form of the disease. The basic variant was present in relatively low amount. Possible reasons for the elevated haptoglobin levels are discussed.

Immunoglobulin abnormalities in patients with myotonic dystrophy

In order to further investigate immunoglobulin (Ig) abnormalities in patients with myotonic dystrophy (MyD), we examined 65 patients with MyD for their serum concentration of IgG in relation to their immunological functions as well as other clinical and laboratory findings. Turnover of IgG was also examined. We found significant and selective reduction of serum IgG in patients with MyD. The serum concentration of IgG in patients with MyD had a significant negative correlation with duration of illness, which suggested that serum IgG levels in MyD decreased constantly throughout the disease course. Peripheral blood lymphocyte subpopulations, including functional T cell subsets, in vitro lymphocyte proliferation, and in vitro IgG production were normal. The plasma cell population in bone marrow was also normal. The IgG turnover study using 125I-labelled IgG as a tracer revealed an increased extravascular IgG pool, and an increased capillary permeability of intravascular IgG into the extravascular compartment, in patients with MyD. These observations suggested that the Ig abnormalities in patients with MyD were not due to a broader immunological derangements as previously postulated by other authors. The abnormal distribution of IgG is a possible factor leading to reduced serum concentration of IgG in patients with MyD.

Immunologic derangement in myotonic dystrophy--abnormal contact sensitization to dinitrochlorobenzene

A broad spectrum of immunologic parameters was investigated in 13 cases of myotonic muscular dystrophy (MyD), including those for cellular immunity which has attracted little attention in the past. One was a 46-year-old woman having both MyD and a thymoma. This association between MyD and thymoma is probably coincidental without biologic significance. There was no evidence of malignancy in the remaining 12 patients. The delayed cutaneous hypersensitivity reaction to dinitrochlorobenzene was anergic in 3 patients and showed impaired positive reactivity in 3 patients, as compared with no failure of response in normal adults or children with Duchenne muscular dystrophy. A high proportion of patients with MyD displayed positive tuberculin reactions, as did controls. Our case of MyD with a thymoma showed marked lymphocytopenia in peripheral blood, but the number of lymphocytes in peripheral blood in the remaining 12 patients was normal. Uptake of tritiated thymidine by lymphocytes in the presence of phytohemagglutinin was normal. Serum gammaglobulin was reduced in 4 patients with MyD. The mean value of serum immunoglobulin level was decreased only in the class of IgG. A wider derangement of immunologic function may occur in MyD than was previously recognized.

Immunoglobulin concentration and Gm allotypes in a family with thirty-three cases of myotonic dystrophy

Serum IgG, IgA, and IgM concentrations were measued in 120 members of a family with 33 cases of Dystrophia myotonica (Dm) and 27 members who were "possibly affected". The Dm individuals had significantly lower serum concentrations of IgG and IgA (P<0.01), while the "possibly affected" did not differ from the matched pair controls. IgG subclass concentrations were measured and GM and Am types determined. The lower concentration of IgA in the affected individuals was not associated with a particular Am type. The concentration of IgG3 was barely lower in the effected than in the controls (P=0.05), but there were no differences for IgG1. When IgG3 concentratin was compared according to Gm haplotype, only the two affected individuals who were Gm gg had a statistically significant lower concentration than the 12 controls (P<0.02). Thus, there is no evidence that a particular subclass of IgG is being hypercatabolized in our Dm patients. A rare Gm haplotype, Gm(-, n, b) had entered the family with two brothers; it is not known whether this codes for an IgG1-IgG3 hybrid molecule or a normal IgG1 molecule with an unknown Gm allele or a gamma 1 deleted Gm haplotype.

Isoelectric focusing and electrophoresis of cerebrospinal fluid proteins in muscular dystrophies and spinal muscular atrophies

In the very few previous investigations of the CSF-proteins in muscular dystrophies the results have generally been reported as normal. In spinal muscular atrophies a barrier-damage pattern of CSF-proteins has been found in amyotrophic lateral sclerosis (ALS). In the present investigation the CSF-proteins were examined by isoelectric focusing and quantitative paper electrophoresis in 13 patients with muscular dystrophies and in 11 patients with spinal muscular atrophies. On isoelectric focusing, CSF-protein abnormalities were found in 85% of the cases with muscular dystrophies and in all patients with spinal muscular atrophies. Differences in the CSF-protein patterns were observed within the group of muscular dystrophies and between these and the cases of spinal muscular atrophies. In ALS and in myotonic dystrophy, abnormal CSF-protein fractions occurred mainly in the alkaline pH-range, while in limb-girdle dystrophy and the patient with facioscapulohumeral dystrophy, aberrant fractions appeared mainly in the acidic region. CSF-protein abnormalities were found in both the alkaline fractions (HAFs) with pI 9.2-9.6 and a fraction with PI 7.1 were found in half of the patients with myotonic dystrophy. The CSF electrophoresis in myotonic dystrophy showed increased levels of beta1-globulin in all cases examined. Signs of barrier-damage were commonly encountered in ALS in contrast to the muscular dystrophies, except for myotonic dystrophy. The results are discussed in terms of possible diagnostic value and with regard to pathogenetic significance, particularly in relation to the current hypothesis of a neural involvement in muscular disorders.

Immunological function in dystrophia myotonica

Humoral and cellular immunity have been investigated in 15 patients with dystrophia myotonica. No abnormalities in total serum levels of the five major immunoglobulin classes were found but there was a rise in the mean serum level of beta(1)A complement. Altogether, 54% of patients failed to make antibody to tetanus toxoid as compared with 1% of controls: 13% of patients failed to make antibody to Salmonella typhi H antigen as compared with no failure of this function in control subjects. There was a reduced uptake of tritiated thymidine by whole blood lymphocyte cultures spontaneously, while in the presence of phytohaemagglutinin (PHA) and both autologous and fetal calf serum the uptake was normal. It is suggested that there may be a wider derangement of immunological function in dystrophia myotonica than previously thought.

[Study of immunglobulins in 5 cases of myotonic dystrophy]

São estudados 5 casos de distrofia miotônica sob o ponto de vista imunoeletroforético. Os resultados obtidos mostram queda acentuada da imunoglobulina G (IgG) em dois casos.